Lester: Judson & 5-speed (IMHO!:)
Yes, the blowers in and of themselves are
worth it but...we no longer have the octanes readily available to run
them, unless you are using 100RON+ racing gas. Otherwise, they are
items for show cars.
The Judson and ( it's British cousin)
Shorrocks were originally intended
for the original low compression (8.3-1)
motors during the days wherein 100+RON
leaded gasolines were readily available.
If you can perfect an alcohol/water delivery system for one, than the
available (at reasonable prices!) modern day lower octane premiums would
compatible, most especially with compression ratios below 8.5-1.
As to vane type blowers, you are better
off with the Shorrocks for two reasons.
1. The Judson runs "interference" fit blades or vanes. The Shorrock's
"clearanced".....MUCH less heating
of the A/F charge with the Shorrocks.
2. While the Shorrock's bearings require
lubrication (off the engine's regular oil
supply), it's vanes do not. Thus, there
is little oil injested into he combustion
chamber with the A/F mixture.
The Judson requires it's own discreet
oil system to supply lubrication to the
blower's bore in view of it's interference
fit vanes. This oil is ingested into the
combustion process as part of the A/F
charge at the rate of about a quart every
500-700 miles. Oil dilutes octanes, and
high compression motors (supercharged)
need all the octanes they can get.
Considering the foregoing, you are much
better off upgrading to a 1275, either
stock or "tuned" to the extent you feel required for your application,
especially in the case of a car used as
a daily driver.
The Datsun 5 speed conversion is a
winner. NO drawbacks...NONE. It's
ALL positive. It is better clearanced...
runs more quietly (by far), cooler and
absorbs less HP generally speaking.
First gear sychro. and the 5th gear
speak for themselves as advantages.
Also, the first three gears of the Datsun
box are of slightly lower ratio than the
ribcase boxi. Thus, a higher rear axle
ratio may be used with sacrificing
acceleration, while at the same time
positively affecting lower rpm cruise
in 4th and 5th.
Better yet, rebuilt Datsun 5 speeds are
going for around $600. Today's rebult
Spridget ribcase boxi are going for
As can be easily seen:
a win/win upgrade if there every was
one, eh? :):)